The risk of communicable disease is not as apparent as other physical risks, such as road traffic, power lines, firearms, or chemical agents. EMS personnel must use the same level of suspicion and precaution whenever approaching a patient. The use of routine practices, as a minimum, is necessary for every patient encounter in order to mitigate this risk. All personnel must take appropriate precautions when a patient presents with any signs or symptoms suspected to be due to an infectious or communicable disease. All EMS and first responder agencies must provide appropriate training that enables personnel to identify at-risk patients and use appropriate personal protective equipment (PPE).
The risk assessment begins with information from an EMS dispatch or communication center, prior to making patient contact. Call-taking procedures should include basic screening information to identify potential communicable disease threats and provide this information to all responding personnel. The screening information can identify patients with symptoms of fever, chills, cough, shortness of breath, or diarrhea. The call-taker can also identify if the patient location, such as nursing home, group home or other institutional setting, poses a potential risk to the responding personnel. This information helps responding personnel to determine what precautions are necessary before they make patient contact.
When patient contact is made, personnel can determine if the patient has a potential risk for a communicable disease. A rapid history and physical examination can help raise suspicion. The following screening questions help identify a patient with a communicable disease.
A screening physical examination will also identify obvious signs of a communicable disease. They may include any new symptom of infection (fever, headache, muscle ache, cough, sputum, weight loss, and exposure history), rash, diarrhea, skin lesions, or draining wounds.
Influenza
Influenza classically presents with the abrupt onset of fever, usually 38–40 °C, sore throat, non-productive cough, myalgias, headache, and chills. Influenza is caused by a virus with three subtypes: A, B, and C. Influenza A causes more severe disease and is mainly responsible for pandemics. Influenza A has different subtypes determined by surface antigens H (hemagglutinin) and N (neuraminidase). Influenza B causes more mild disease and mainly affects children. Influenza C rarely causes human illness and has not been associated with epidemics [5].
Influenza transmission occurs primarily through airborne spread when a person coughs or sneezes, but may also occur through direct contact of surfaces contaminated with respiratory secretions. Hand-washing and shielding coughs and sneezes help prevent spread. Influenza is transmissible from one day before symptom onset to about 5 days after symptoms begin and may last up to 10 days in children. Time from infection to development of symptoms is 1–4 days [6].
Influenza has been responsible for at least 31 pandemics in history. The most lethal “Spanish flu” pandemic of 1918–1919 is estimated to have caused 40 million deaths globally with 700,000 of those deaths occurring in the USA in a single year. In this pandemic, deaths occurred mainly in healthy 20–40 year olds, which differs from the usual young children and elderly pattern of mortality and morbidity in the seasonal outbreaks of influenza.
Influenza vaccine is the principal means of preventing influenza morbidity and mortality. The vaccine changes yearly based on the antigenic and genetic composition of circulating strains of influenza A and B found in January to March, when influenza reaches its peak activity. When the vaccine strain is similar to the circulating strain, influenza vaccine is effective in protecting from illness 70–90% of those younger than age 65 who are vaccinated. Among those aged 65 and older, the vaccine is 30–40% effective in preventing illness, 50–60% effective in preventing hospitalization, and up to 80% effective in preventing death. EMS personnel should be immunized annually, typically in October.
Four antiviral drugs are available for preventing and treating influenza in the US. When used for prevention of influenza, they can be 70–90% effective. Antiviral agents should be used as an adjunct to vaccination, but should not replace vaccination. The Centers for Disease Control and Prevention (CDC) recommends influenza antivirals for individuals who have not as yet been vaccinated at the time of exposure, or who have a contraindication to vaccination, and are also at high risk of influenza complications. Also, if an influenza outbreak is caused by a variant strain of influenza not controlled by vaccination, chemoprophylaxis should be considered for health care providers caring for patients at high risk of influenza complications, regardless of their vaccination status. In the setting of an influenza outbreak, EMS systems may opt to restrict duties for EMS providers who are not immunized or who have not yet received prophylactic antiviral therapy in an attempt to prevent spread of the outbreak [5].
Avian influenza
Influenza A virus infects humans and also can be found naturally in birds. Wild birds carry a type of influenza A virus, called avian influenza virus, in their intestines and usually do not get sick from them. However, avian influenza virus can make domesticated birds (including chickens, turkeys, and ducks) quite ill and lead to death.
The avian influenza virus is chiefly found in birds, but infection in humans from contact with infected poultry has been reported since 1996. A particular subtype of avian influenza A virus, H5N1, is highly contagious and deadly among birds. In 1997 in Hong Kong, an outbreak of avian influenza H5N1 occurred not only in poultry but also in 18 humans, six of whom died. In subsequent infections of avian influenza H5N1 in humans, more than half of those infected with the virus have died. In contrast to seasonal influenza, most cases of avian influenza H5N1 have occurred in young adults and healthy children who have come into contact with infected poultry, or surfaces contaminated with H5N1 virus. By the end of 2007, there were 346 documented human infections with influenza H5N1 and 213 deaths (62%). Although transmission of avian influenza H5N1 from human to human is rare, inefficient, and unsustained, there is concern that the H5N1 virus could adapt and acquire the ability for sustained transmission in the human population. If the H5N1 virus could gain the ability to transmit easily from person to person, a global influenza pandemic could occur. A vaccine is now available for H5N1, as a two-dose regimen. It is not currently available or advocated for use in the general population, but is being stockpiled by several countries. The H5N1 virus is resistant to the adamantanes, but likely sensitive to the neuraminidase inhibitors [7].
In April 2009, a novel influenza A (H1N1) virus, similar to but genetically and antigenically distinct from other influenza A (H1N1) viruses, was determined to be the cause of respiratory illnesses that spread across North America and many areas of the world. Influenza morbidity caused by the 2009 pandemic influenza A (H1N1) remained above seasonal baselines throughout spring and summer 2009, and was the first pandemic since 1968. Data from epidemiological studies conducted during the 2009 influenza A (H1N1) pandemic indicate that the risk for influenza complications among adults aged 19–64 years who had 2009 pandemic influenza A (H1N1) was greater than typically occurs for seasonal influenza [8].
Tuberculosis
Tuberculosis is caused by the Mycobacterium tuberculosis complex. The majority of active TB is pulmonary (70%), while the remainder is extrapulmonary (30%). Patients with active pulmonary TB will typically present with cough, scant amounts of non-purulent sputum and possibly hemoptysis. Systemic signs such as weight loss, loss of appetite, chills, night sweats, fever, and fatigue may also be present. Clinically, the EMS provider will be unable to distinguish pulmonary TB from other respiratory illnesses. However, certain risk factors may alert the EMS provider to the possibility of tuberculosis: immigration from a high-prevalence country, homelessness, exposure to active pulmonary TB, silicosis, HIV infection, chronic renal failure, cancer, transplantation, or any other immunosuppressed state [9,10].
Active pulmonary TB is transmitted via droplet nuclei from people with pulmonary tuberculosis during coughing, sneezing, speaking, or singing. Procedures such as intubation or bronchoscopies are high risk for the transmission of TB. Respiratory secretions on a surface rapidly lose the potential for infection. The probability of infection is related to duration of exposure, distance from the case, concentration of bacilli in droplets, ventilation in the room, and the susceptibility of the host exposed. Effective medical therapy eliminates communicability within 2–4 weeks of starting treatment [11].
If transporting a patient who is known to have or suspected of having TB, respiratory precautions should be followed by EMS providers, including use of submicron masks. Patients should cover their mouths when coughing or sneezing, or wear surgical masks. In the event of suspected exposure to a patient with active pulmonary tuberculosis, report the case and the exposure to the EMS system or public health authority. Close contacts should be monitored for the development of active TB symptoms. Two tuberculin skin tests should be performed, based on public health recommendations, on those closely exposed to patients with active TB [12]. Because the incubation period after contact ranges from 2 to 10 weeks, the first test is typically done as soon as possible after exposure, and the second test is typically done 8–12 weeks after the exposure. If the EMS provider or contact develops either active TB with symptoms or latent asymptomatic TB, as diagnosed with a new positive TB skin test, treatment should be offered.
Treatment for latent TB is typically isoniazid (INH) for 6–9 months [13]. This single-drug regimen is 65–80% effective. For active TB, a four-drug regimen is typically used for 2 months: isoniazid, rifampin, pyrazinamide, and ethambutol. This is followed by INH and rifampin for an additional 4 months. Several forms of multidrug-resistant TB and extensively drug-resistant TB have been identified [14]. These forms require an aggressive, multidrug regimen for prolonged periods of time and are dependent on the organism’s patterns of drug sensitivity and resistance. In all cases, a physician skilled in management of TB must initiate and monitor treatment and provide suitable follow-up. Public health officials must also be notified [15].
SARS and related coronaviruses
It is difficult to distinguish SARS from other respiratory infections because patients present with symptoms similar to other febrile respiratory illnesses [16,17]. Fever is the most common and earliest symptom of SARS, often accompanied by headache, malaise or myalgia [18]. In patients with SARS, high fever, diarrhea, and vomiting were more common compared to patients with other respiratory illnesses [19]. Cough occurred later in the course of disease and patients were less likely to have rhinorrhea or sore throat compared to other lower respiratory tract illness [20]. Since clinical features alone cannot reliably distinguish SARS from other respiratory illnesses, knowledge of contacts is essential [21]. Contact with known SARS patients, contact with SARS-affected areas, or linkage to a cluster of pneumonia cases should be obtained in the history [22].
Severe acute respiratory syndrome was first recognized in 2003 after outbreaks occurred in Toronto, Singapore, Vietnam, Taiwan, and China [23]. The illness is caused by a coronavirus. About 11% of those who develop SARS eventually die, usually due to respiratory failure. The case fatality is less than 1% for SARS patients less than age 24 and up to 50% for those age 65 and greater or those with comorbid illness [24].
The coronavirus is found in respiratory secretions, urine, and fecal matter. Transmission is via droplets spread from respiratory secretions, with a high risk of transmission during intubation and procedures which aerosolize respiratory secretions. Transmission can also occur from fecal or urine contamination of surfaces. There have been no confirmed cases of transmission from asymptomatic cases.
If SARS is suspected, EMS providers must use all routine practices and additional precautions [25]. EMS systems may also elect to limit or avoid any procedures that may increase risk to EMS personnel. These include tracheal intubation, deep suctioning, use of non-invasive ventilatory support, administration of nebulized medication, and any other procedure that may aerosolize respiratory secretions. During the SARS outbreaks in Toronto, EMS medical direction modified medical directives such that paramedics did not intubate patients or deliver nebulized therapy in the prehospital setting [26]. Finally, EMS personnel and systems should also notify the receiving facility of a patient suspected of SARS, permitting the staff to have appropriate PPE in place and a suitable isolation room prepared for the patient [27,28].
